Paraffin removal process for oil wells



Wm; M, M5 T. J. lDEERDOFF PARAFFIN REMOVAL PROCESS FOR OIL WELLS 2Sheets-Sheet 1 Filed June 1, 1954 W x E 0 A M J r w W lm? 5. 1%7 1 m 7M77777 x? H/ \M Filed June 1, 1954 T. J. DEERDOFF PARAFFIN REMOVALPROCESS FOR OIL. WELLS J RU MW 2 Sheets-Sheet 2 VALVE OPENED VALVECLOSED INVENTOR.

PARAFFIN REMOVAL PRESS FOR OIL WELLS Thomas J. Deerdoif, lheveliand, Texassignor, by mesne assignments, to llarat'rac, Inc, a corporation of NewMexico Application June 1, 1954, Serial No. 433,567

7 Claims. (Cl. 166-41) The present invention relates to a method ofremoving parafiin deposits from the casing, tubing, and pump rods of oilwells.

The primary object of the invention is to provide a novel method oftreating oil wells to remove from and prevent the further accumulationof paraffin on the well tubing and pump or sucker rods, which processnecessitates no pulling of the well tubing or pump rods and whichprocess of treatment may ordinarily be completed and the well put backin operation in a matter of from one-half to two hours.

Paraffin deposition in oil well pumping equipment presents aparticularly difiicult problem in the pumping of oil from wells in theminimum time and at a minimum cost since such deposition on the wellcasing, tubing and sucker rods is dependent upon temperature variationsin the well, the physical and chemical nature of the oil from which theparaffin is deposited, the nature of the paraflin, and to a lesserextent, to the tubing size and the rate of oil flow from the well.

In the Texas-Oklahoma oil field area, wells are often drilled to a depthof 6000 feet, and over. The bottom hole temperatures of the wells inthis area average somewhere in the neighborhood of 120 degrees F.Paratfin is normally held in solution at these temperatures. Underaverage pressure and other well conditions, paraflin begins to congealout of the petroleum and deposit and form encrustations on the welltubing and pump rods at approximately 100 degrees P. which temperatureoccurs at a depth of approximately 3000 feet. The conditions, however,do vary considerably and there may be no substantial paraffinencrustation on the tubing and pump rods below a depth of around 1200feet. But, since the temperature decreases from the bottom to the top ofthe well, the encrustation increases in thickness as the top of the wellis approached.

The paraiiin encrustation on the well tubing and pump rods in some casescompletely chokes the well causing complete stoppage. More often,however, before this condition is reached, attempts are made to reducethe paraflin congestion in the tubing in order to bring the well back tofull pumping capacity.

Numerous methods have heretofore evolved for treating oil Wells toremove parafiin depositions on the well equipment. The treatments fallinto many categories such as treating with heated steam or oil to remeltthe parafiin in the solution, treating the paraflin with solvents,physical scraping of the parafiin from the affected areas, treating theformation oil with parafiin deposition inhibiting solvents, and morerecently, the provision of hollow sucker or pump rods through which aportion of the oil flows at an increased rate with considerableturbulence.

Although all of these methods of treatment have some advantages, theyalso possess many disadvantages which are well known to those skilled inthe art.

In treating a well, in accordance with my invention, attention isdirected to the drawings wherein:

atertt Patented Nov. 13, 1956 Figure 1 represents a cross-sectional viewof a pumping oil well which is partially choked through the incident ofparafiin depositions or accumulations on the sucker rods and the tubing;

Figure 2 is a cross-sectional view of the well in the initial stages oftreatment in accordance with the present invention; and

Figure 3 is a cross-sectional view of the well after treatment and readyto resume pumping operations.

In the drawings, the well is designated in its entirety by the numeral10 and is shown, as is customary, as comprising a well casing 12, welltubing 14, pump 16 for pumping oil from the formation through the tubing14 and pump or sucker rods 18 for reciprocating the pump piston withinthe pump cylinder or working barrel 16. As shown in the drawings, thepump is disposed within the oil formation 20 at the bottom of the welland in the ordinary operation of the well, oil is pumped up through thetubing 14 and out the flow line 22.

As the oil is drawn up through the tubing 14, the temperature isconstantly decreasing until a temperature is reached wherein paraffinbegins to congeal out of the oil and deposit or accumulate on the innersurface of the well tubing and the outer surface of the sucker rods.This deposition is designated generally at 24.

When this condition results, as shown in Figure l, the well tubing ischoked and the normal flow of oil cannot be pumped through the tubing.Consequently, treatment of the tubing and sucker rods is necessary torestore the well to its normal pumping capacity.

In order to prepare the well for treatment in accordance with myinvention, the barrel 16 is first drawn up out of its seated pumpingposition at least the length of the pump stroke, as indicated in Figure2.

Then, the sucker rods 18 are reciprocated in the well tubing 14 while aplurality of layers of treating materials are successively forced downthe well tubing, the materials consisting of an emulsion breaking layer,a light lubricating layer, and a heavy lubricating layer, the layersbeing forced down the tubing by hot oil to form a progressivelyincreasing downwardly moving column, the layers and the oil entering thetubing through line 26 opening intothe upper end of this tubing.

The proper depth in the well tubing to which the composite layers andhot oil must be forced is easily determined by the sudden pressure dropwhich occurs when the treating layers have reached a point in the tubingbelow the lowest point of paraflin accumulation thereon.

The crux of the present invention lies in the formation of the fluidcolumn forced down the well tubing wherein the column comprisessuccessive layers from bottom to top of a water in oil emulsion breaker28, lubricating or lubrication grease layers 30, 32, followed by hot oil34.

For the emulsion layer, almost any known demulsification agent forpreventing, breaking, or resolving emulsions of the water in oil typemay be utilized. Such demulsification agents, usually comprising asaponifiable oil and an alkali, exist in a wide variety and are wellknown in the art, several different agents being represented in PatentsNos. 1,454,616, 1,858,156, 1,976,602, 2,522,523, these patents beingcomparatively representative of the demulsification agents now in use.The ordinary use for these demulsification agents is, of course, toseparate the water from water-in-oil emulsions after oil has been pumpedfrom the well. However, I have found extremely beneficial and uniqueresults accrue in the treatment of the oil wells themselves with suchdemulsification agents in the removal of parafiin encrustations oraccumulations from the well tubing and sucker rods. Although it is notcertain exactly what occurs with the use of the demulsification agent,in this deparafiinizing treatment, the agent appears to remove the saltbrine from the parafiin, tubing and sucker rods to prepare the tubingand sucker rods for the coating of these members by the lubricatinglayer.

The lubrication layer consists of two separate and distinct portions, alight lubrication layer and a heavy lubrication layer. The lightlubrication layer is formed by cutting chassis grease from its normalconsistency to a Saybolt viscosity of approximately 5070 at 100 degreesF. This light lubrication layer prepares the tubing and sucker rods forthe heavy lubrication layer which follows.

The heavy lubrication layer is in the form of a heavy chassislubricating grease, having a Saybolt viscosity approaching 500 .or aboveat 210 degrees F. and immediately follows the light lubrication layerinto the well tubing. The entire mass is forced through the tubing byhot oil, preferably around 140 degrees P. which melts the paraffin fromthe sucker rods and the tubing wall.

Ordinarily, if only hot oil is utilized to melt the paraffin from thetubing and sucker rods, the treatment is short lived indeed, sinceimmediately upon expulsion of the hot oil from the tubing, paraffinagain begins to accumulate on the tubing and sucker rods, necessitatingfrequent treatment and affording generally inadequate results.

However, when this hot oil is utilized with the heavy and lightlubrication layers and the demulsification plug in a batch treatment ofthe well, the paraflin is not only completely removed, but a lubricationcoating of the eavy grease and oil of the lubrication layers is formedon the walls of the sucker rods and the tubing which prevents theaccumulation or encrustation of parafiin thereon for extremely longperiods of time. The uniformity and duration of the coating is believedto result from the emulsified salt brine removal from the Well equipmentby the demulsification plug.

This treatment has been utilized with outstanding success in thetreatment of pumping oil wells for the removal of paraflin from the wellequipment, the treatment taking anywhere from one-half to two hours, thewell being restored to normal operation immediately following thetreatment.

Example 1 Well No. 2, situated on the Hamill-Hooper lease in HockleyCounty, Texas, had been treated with various paraffin removal treatmentsapproximately every thirty days for the removal of parafiin therefromand it became completely stuck if permitted to run sixty days or longerwithout such treatment.

On November 13, 1953, this well was treated in. accordance with myinvention to a depth of 1100 feet. The treatment took approximately halfan hour and immediately after this'treatment the well continued toproduce by pumping in the usual and customary manner. Eighty days aftertreatment, approximately 40 joints of the sucker rod were pulled and thetubing and rod were found to be clean and completely free of paraflin.The well was producing from a pay zone situated 4894 feet below thesurface of the ground and the fluid level in the casing. and the tubingwas approximately 3800 to 3900 feet below the surface of the ground.

Example 2 parently the treatment was sufficient to slip on through thewell tubing because the well was checked on February 6, 1954 and foundto be completely clear of parafiin.

Example 3 David Parsons well No. 3 of Sun Oil Company in Hockley County,Texas, was treated in accordance with the invention in December, 1952.At that time the well was producing from a zine approximately 4996 feetbelow the surface of the ground. The fluid level in the casing andtubing at that time was approximately 4196 feet below the surface of theground and the well Was parafiined to a depth of approximately 1400feet; the treatment was carried out throughout the 1400 feet. Prior tothis treatment, the well had been treated by other methods approximatelyevery thirty days in order to avoid becoming completely choked. Aftertreatment in accordance with the invention, the well was checked atthirty day intervals for sixteen consecutive months before there was anyadherence of paraffin noted on the sucker rods. It was not until the endof approximately eighteen months without further treatment that the wellbecame completely choked with parafiin.

The reciprocation of the sucker rods during the forcing of the parafiinremoving ingredients down the well tubing causes sufficient agitation ofthe demulsification plug to thoroughly separate all the salt water brinedisbursed in the oil and paraffin clinging to the tubing and sucker rodsto prepare the tubing and rods for a proper lubrication coating while atthe same time mixing the heavy and light lubrication layers with oneanother and with the hot oil to form a continuous coating on the tubingand the sucker rods, which coating prevents the redeposition oraccumulation of paraffin on these members during the normal pumpingoperation of the well, allowing paraffin ordinarily separating from theoil during pumping to slip through the tubing and around the sucker rodswithout deposition. The effect of this treatment is twofold in that theparaffin is not only removed from the tubing and sucker rods, but thetubing and sucker rods are prepared for the reception of a lasting,substantially uniform lubrication coating formed by the heavy lubricantand the light lubricant of the lubrication plug mixing with the hot oiland uniformly coating the tubing. This coating prevents the accumulationof paraffin on the tubing or sucker rods even though this paraffin doescongeal out of the crude oil as it is pumped through the well since noadhering surface is left on which the parafiin may cling.

Were it not for the use of the demulsification agent initially in thetreating process, the tubing and sucker rods would not be suficientlyprepared. for the reception of a more or less uniform lubricationcoating thereon, the coating being instead spotty and nonuniform causingthe quick accumulation of paraffin on the insufficiently lubricatedareas, which areas would occur from the higher incidence of salt Watereroded bare areas along the tubing and sucker rods which ordinarilyoccur through the customary operation of the well and furnish footholdsfor the paraffin deposition.

. From the foregoing description, the process and its application willbe readily apparent to those skilled in the art.

What is claimed as new is as follows:

1. A method of removing deposited paraflin encrustation from the welltubing and pump rods of pumping oil wells which comprises sequentiallyforcing layers of an emulsion breaker, a lubricating grease and hot oildown the. well tubing thereby removing the encrusted paraffin from thewell tubing and pump rods and depositing a lubricant coating on the welltubing,.agitating the mass formed by the successive layers durin. theirpassage down the well tubing by reciprocating the pump rods.

2. A method of removing deposited paraflin encrustaa tion from the welltubing and pump rods of pumping oil wells which comprises sequentiallyforcing an emulsion breaker, a heavy lubricant and hot oil down the welltubing thereby removing the encrusted paraffin from the Well tubing andpump rods, and coating the pump rods and tubing with a lubrication filmpreventing redeposition of paratiin thereon.

3. A method for removing deposited paraflin encrustation from the welltubing and pumping rods of pumping oil wells which comprisessequentially forcing a water-inoil demulsification material, a heavylubricating material, and a paraflln solvent miscible with thelubricating material into the well tubing.

4. A process for removing paraflin depositions from oil well tubing andinhibiting further paraflin deposition of such tubing comprising thesteps of forcing a water in-oil demulsification agent down the welltubing, then forcing a heavy lubricant down the well tubing, and toreinghot oil down the tubing, agitating the mixture during its passage downthe tubing to remove paraifin depositions from the tubing, then removingthe mixture 'from the tubing by releasing the forcing pressure andthereby causing a substantially uniform deposition of a lubricationcoating on the Well tubing.

5. A process for removing parafiin depositions from the tubing andsucker rods of pumping oil wells which comprises lifting the workingbarrel from its pumping seat in the tubing, forcing a progressivelyincreasing downwardly moving fluid column down the well tubingcomprising successive layers of a water-in-oil demulsification agent, athick, viscous lubricating grease and hot oil, longitudinallyreciprocating the sucker rods while forcing the mixture down the tubingto blend the oil and grease layers with one another, discontinuing theintroduction of the fluid when the fluid column is of a length equal tothe depth of the paraffin deposition in the tubing, then discharging thefluid column through the top of the tubing.

6. A process for simultaneously removing paraihn depositions from thetubing and sucker rods of pumping oil Wells and treating the tubing andsucker rods for prevention of further parafifln deposition, the processcomprising forcing down the well tubing a progressively increasingdownwardly moving fluid column comprising successive layers from thebottom of the column to the top of a water-in-oil demulsification agent,a thick viscous lubricant, and hot oil, breaking water'in-oil emulsionsin the oil clinging to the sucker rods and tubing with thedemulsification agent and melting deposited paraffin on the tubing andsucker rods into the hot oil, discontinuing the introduction of thefluid when the fluid column i of a length equal to the depth of paraffindeposition in the tubing, then withdrawing the fluid column through thetop of the tubing causing the deposition of a substantially uniformlubricant coating on the tubing and sucker rods.

7. The process of claim 6 wherein the lubricant coating is free fromwater-in-oil emulsions and is more viscous than the oil normally pumpedfrom the well.

References Cited in the file of this patent UNITED STATES PATENTS2,300,348 Dana a Oct. 27, 1942 2,364,222 Kaufman Dec. 5, 1944 2,658,036Core et a1. Nov. 3, 1953

1. A METHOD OF REMOVING DEPOSITED PARAFFIN ENCRUSTATION FROM THE WELLTUBING AND PUMP RODS OF PUMPING OIL WELLS WHICH COMPRISES SEQUENTIALLYFORCING LAYERS OF AN EMULSION BREAKER, A LUBRICATING GREASE AND HOT OILDOWN THE WELL TUBING THEREBY REMOVING THE ENCRUSTED PARAFFIN